<?php
	session_start();

	class Session
	{
		private function __construct() {}
		private function __destruct() {}
		private function __clone() {}
		
		public static function set($key, $val = null)
		{
			$_SESSION[$key] = $val;
		}
		
		public static function get($key)
		{
			if (!array_key_exists($key, $_SESSION))
				return null;
			return $_SESSION[$key];
		}
		
		public static function has($key)
		{
			return array_key_exists($key, $_SESSION);
		}
		
		public static function remove($key)
		{
			if (array_key_exists($key, $_SESSION))
				unset($_SESSION[$key]);
		}
	}
?>